For example, in portable electrically powered tools such as motorized drivers, inner-rotor-type brushless motors (brushless DC motors) capable of size reduction are often used. Such a brushless motor includes: a stator core having a cylindrical yoke portion and teeth portions protruding from an inner circumferential surface of the yoke portion; and a rotor that rotates inside the stator core. Coils are wound around the teeth portions, and a permanent magnet is provided in the rotor. The teeth portions magnetized by an electric current flowing through the coils apply a magnetic force to the permanent magnet of the rotor, and the rotor thereby rotates.
At this time, as a counteraction to the rotation of the rotor, the teeth portions also receive a magnetic force from the permanent magnet of the rotor. For this reason, in order to prevent the stator core from rotating or moving, it is necessary to fix the stator core to, for example, a housing such as tool body of an electrically powered tool or the like. For example, Patent Literature (PTL) 1 discloses a configuration in which the outer circumferential surface of the yoke portion is fixed by the inner circumferential surface of the cylindrical housing.